fenix
/
cpdf-source
mirror of https://github.com/johnwhitington/cpdf-source.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Finish new -jpeg-to-jpeg docs

This commit is contained in:
John Whitington 2024-11-07 15:26:13 +00:00
parent de56377d23
commit 37de53f33e
2 changed files with 20 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

BIN
cpdfmanual.pdf
View File

Binary file not shown.

28
cpdfmanual.tex
View File

@ -3806,14 +3806,13 @@ The \texttt{-dump-attachments} operation, when given a PDF file and a directory
\noindent\small\verb!cpdf -process-images [-process-images-info] in.pdf [<range>]!\\ \noindent\small\verb!cpdf -process-images [-process-images-info] in.pdf [<range>]!\\
\noindent\small\verb! [-im <filename>] [-jbig2enc <filename>]!\\ \noindent\small\verb! [-im <filename>] [-jbig2enc <filename>]!\\
\noindent\small\verb! [-lossless-resample[-dpi] <n> | -lossless-to-jpeg <n>]!\\ \noindent\small\verb! [-lossless-resample[-dpi] <n> | -lossless-to-jpeg <n>]!\\
\noindent\small\verb! [-jpeg-to-jpeg <n>] [-1bpp-method <method>]!\\ \noindent\small\verb! [-jpeg-to-jpeg <n>] [-jpeg-to-jpeg-scale <n>]!\\
\noindent\small\verb! [-jbig2-lossy-threshold <n>]!\\ \noindent\small\verb! [-jpeg-to-jpeg-dpi <n>] [-1bpp-method <method>]!\\
\noindent\small\verb! [-pixel-threshold <n>] [-length-threshold <n>]!\\ \noindent\small\verb! [-jbig2-lossy-threshold <n>] [-pixel-threshold <n>]!\\
\noindent\small\verb! [-percentage-threshold <n>] [-dpi-threshold <n>]!\\ \noindent\small\verb! [-length-threshold <n>] [-percentage-threshold <n>]!\\
\noindent\small\verb! [-resample-interpolate]!\\ \noindent\small\verb! [-dpi-threshold <n>] [-resample-interpolate]!\\
\noindent\small\verb! -o out.pdf! \noindent\small\verb! -o out.pdf!
\end{framed} \end{framed}
\section{Extracting images} \section{Extracting images}
@ -3985,14 +3984,27 @@ Option & Effect & Default value\\\hline
\noindent\small\verb!cpdf -process-images -im magick -lossless-resample 80 in.pdf -o out.pdf! \noindent\small\verb!cpdf -process-images -im magick -lossless-resample 80 in.pdf -o out.pdf!
\end{framed} \end{framed}
%FIXME check what 80 means here \noindent This will resample losslessly-compressed images to be 80 percent of the original width and height. By default, there will be no interpolation. To use interpolation, which may result in slightly larger data, add \texttt{-resample-interpolate}. To use a DPI target instead, use \texttt{-lossless-resample-dpi} instead:
\noindent This will resample losslessly-compressed images to contain 80 percent of the original pixels. By default, there will be no interpolation. To use interpolation, which may result in slightly larger data, add \texttt{-resample-interpolate}. To use a DPI target instead, use \texttt{-lossless-resample-dpi} instead:
\begin{framed} \begin{framed}
\noindent\small\verb!cpdf -process-images -im magick -lossless-resample-dpi 300!\\ \noindent\small\verb!cpdf -process-images -im magick -lossless-resample-dpi 300!\\
\noindent\small\verb! in.pdf -o out.pdf! \noindent\small\verb! in.pdf -o out.pdf!
\end{framed} \end{framed}
\noindent We can also use resampling with \texttt{-jpeg-to-jpeg}, buy specifying \texttt{-jpeg-to-jpeg-scale}:
\begin{framed}
\noindent\small\verb!cpdf -process-images -im magick -jpeg-to-jpeg 70 -jpeg-to-jpeg-scale 50!\\
\noindent\small\verb! in.pdf -o out.pdf!
\end{framed}
\noindent We can alternatively use a DPI target:
\begin{framed}
\noindent\small\verb!cpdf -process-images -im magick -jpeg-to-jpeg 70 -jpeg-to-jpeg-dpi 150!\\
\noindent\small\verb! in.pdf -o out.pdf!
\end{framed}
\noindent The methods so far introduced do not operate on 1 bit per pixel data. Different compression mechanisms are typically in use, and we need a different approach. The \texttt{-1bpp-method} option specifies what to do with losslessly compressed 1 bit-per-pixel images. \noindent The methods so far introduced do not operate on 1 bit per pixel data. Different compression mechanisms are typically in use, and we need a different approach. The \texttt{-1bpp-method} option specifies what to do with losslessly compressed 1 bit-per-pixel images.
\bigskip \bigskip